Method for producing a component from a composite material comprising a metal matrix and incorporated intermetallic phases

Abstract

The present invention relates to a method for producing a component of a composite material comprising a metal matrix and incorporated intermetallic phases, which method comprises providing powders of at least one member of the group which comprises pure chemical elements, alloys, chemical compounds and material composites, the powder corresponding overall to the chemical composition which the composite material to be produced is intended to have, each individual powder being different to the chemical composition of the composite material to be produced, compacting the powders, bonding the powders to one another to form a unit and thermoplastically shaping the unit.

Claims

1. A method for producing a component of a composite material comprising a metal matrix and incorporated intermetallic phases, wherein the method comprises: providing powders of at least one member from the group which comprises pure chemical elements, alloys, chemical compounds and material composites, the powders corresponding overall to a chemical composition of the composite material of the component, each individual powder having a chemical composition which is different from the chemical composition of the composite material of the component, compacting the powders, bonding the powders to one another to form a unit and thermoplastically shaping the unit, the composition of the composite material of the component being as follows: from 40 at % to 55 at % molybdenum, from 5 at % to 20 at % silicon, from 5 at % to 15 at % boron, from 20 at % to 40 at % titanium, from 1 at % to 5 at % iron, from 0 at % to 5 at % yttrium, from 0 at % to 5 at % hafnium, from 0 at % to 5 at % zirconium, from 0 at % to 5 at % niobium, from 0 at % to 2 at % tungsten, and unavoidable impurities.

2. The method of claim 1, wherein compaction and/or bonding of the powders and/or thermoplastic shaping of the unit are carried out in a single step.

3. The method of claim 1, wherein compaction and/or bonding of the powders and/or thermoplastic shaping of the unit are carried out in separate individual steps.

4. The method of claim 1, wherein prior to compaction of the powders the powders are mixed.

5. The method of claim 1, wherein after the thermoplastic shaping, finishing is carried out, the finishing comprising at least one of a heat treatment, a mechanical finishing, a surface treatment, and coating.

6. The method of claim 1, wherein the powders comprise one or more of elemental particles, alloy particles, coated particles, particles of intermetallic phases, chemical compounds.

7. The method of claim 1, wherein the metal matrix is formed by a molybdenum alloy in which silicides are incorporated.

8. The method of claim 1, wherein the compaction is carried out by cold pressing.

9. The method of claim 1, wherein the bonding is carried out by sintering.

10. The method of claim 1, wherein the compaction and bonding of the powders comprises one or more of pressure sintering, hot pressing, hot pressing of evacuated capsules, hot isostatic pressing.

11. The method of claim 1, wherein prior to the thermoplastic deformation at least one unit is melted and subsequently resolidified.

12. The method of claim 1, wherein the thermoplastic deformation is carried out by one or more of hot pressing, hot pressing of evacuated capsules, hot isostatic pressing, die forging, isothermal die forging, hot die forging, rolling, hammering, extrusion, freeform forging.

13. The method of claim 1, wherein after the thermoplastic shaping a heat treatment is carried out at a temperature in a range from 100 C. to 200 C. below a recrystallization temperature.

14. The method of claim 1, wherein the composition of the composite material of the component is as follows: from 45 at % to 52 at % molybdenum, from 8 at % to 15 at % silicon, from 7 at % to 10 at % boron, from 25 at % to 30 at % titanium, from 1 at % to 3 at % iron, from 0 at % to 3 at % yttrium, from 0 at % to 3 at % hafnium, from 0 at % to 2 at % zirconium, from 0 at % to 2 at % niobium, from 0 at % to 1 at % tungsten, and unavoidable impurities.

15. The method of claim 1, wherein the composition of the composite material of the component comprises one or more of: from 45 at % to 52 at % molybdenum, from 8 at % to 15 at % silicon, from 7 at % to 10 at % boron, from 25 at % to 30 at % titanium, from 1 at % to 3 at % iron, from 0 at % to 3 at % yttrium, from 0 at % to 3 at % hafnium, from 0 at % to 2 at % zirconium, from 0 at % to 2 at % niobium, from 0 at % to 1 at % tungsten, and unavoidable impurities.

16. The method of claim 1, wherein the component is a component of a turbomachine.

17. The method of claim 1, wherein the component is component of an aircraft engine.

18. The method of claim 1, wherein powders of pure molybdenum and/or molybdenum alloys are mixed with silicide powders.

19. The method of claim 18, wherein the silicide powders comprise one or both of Mo(Ti).sub.5SiB.sub.2 and/or Mo(Ti).sub.5Si.sub.3.

20. The method of claim 1, wherein pure element powders are mixed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the appended drawings,

(2) FIG. 1 shows a flowchart of a first embodiment,

(3) FIG. 2 shows a flowchart of a second embodiment,

(4) FIG. 3 shows a flowchart of a third embodiment,

(5) FIG. 4 shows a flowchart of a fourth embodiment,

(6) FIG. 5 shows a flowchart of a fifth embodiment,

(7) FIG. 6 shows a flowchart of a sixth embodiment,

(8) FIG. 7 shows a flowchart of a seventh embodiment,

(9) FIG. 8 shows a flowchart of an eighth embodiment,

(10) FIG. 9 shows a flowchart of a ninth embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

(11) The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description in combination with the drawings making apparent to those of skill in the art how the several forms of the present invention may be embodied in practice.

(12) In the first embodiment according to FIG. 1, powders of pure metal particles, i.e. particles which contain only one chemical element, alloy particles which are formed from alloys, as well as coated particles and/or particles of intermetallic phases and/or chemical compounds, all of which differ individually from the chemical composition of the component to be produced, are provided in the corresponding proportion (Step 10) so that together, taking into account shrinkages during the production method, the chemical composition of the component to be produced can be achieved. For example, particles of pure molybdenum and/or molybdenum alloys, for example alloys with tungsten, niobium, titanium, iron, zirconium, may be mixed with silicide powders with the composition Mo(Ti).sub.5SiB.sub.2 and/or Mo(Ti).sub.5Si.sub.3, in which case the molybdenum in the intermetallic compounds may be partially replaced with titanium, as is indicated by the term in brackets. Furthermore, the molybdenum alloys may optionally contain yttrium and/or hafnium. As an alternative, pure elemental powders of molybdenum, silicon, boron, titanium, iron, zirconium, tungsten and/or niobium, and optionally yttrium and/or hafnium, may be mixed.

(13) Advantageous properties of the final mixture with a balanced property profile in terms of creep resistance, static strength, fracture toughness, ductility, oxidation resistance and low density, have been achieved with the following exemplary compositions (data respectively in at %), which may also comprise small amounts of other elements as unavoidable impurities:

(14) TABLE-US-00001 molybdenum silicon boron titanium iron yttrium zirconium niobium Tungsten 49.5 12.5 8.5 27.5 2.0 0 0 0 0 48.5 13.5 8.5 26.5 2.0 0 1.0 0 0 51 10.0 8.5 27.5 2.0 0 1.0 0 0 46.5 12.5 8.5 27.5 2.0 2.0 1.0 0 0 46.5 12.5 8.5 27.5 2.0 2.0 0 1.0 0 46.5 12.5 8.5 27.5 2.0 2.0 0 0 1.0

(15) In these compositions, yttrium may optionally be replaced partially or fully with hafnium.

(16) These powder particles are mixed (Step 11) and subsequently introduced into a capsule which may already be precontoured in a manner similar to the component to be produced, i.e. it may have a similar shape to the component to be produced. Although the precontouring of the capsule is often advantageous, it is not compulsory. Instead, the capsule may also have a shape which is not close to final contour, for example a cylindrical shape when the final component is intended to be a blade. The final shape of the component may in such a case be achieved by a subsequent method step in which material is removed, for example by erosion or milling.

(17) The capsule isexcept of course from the powder particles with which it is filledevacuated, then closed and subsequently subjected in a mechanical press to a hot pressing method (Step 12), in which both the compaction of the powder and the bonding of the powder particles to one another and the thermoplastic shaping take place in one step.

(18) Subsequently, the component produced in this way may be subjected to a heat treatment in order to adjust the structure in the desired way and/or to eliminate internal stresses. Mechanical finishing may then be carried out, during which the capsule may for example be removed. The mechanical processing may be followed by further steps of surface treatment and coating with oxidation protection layers and/or antiwear layers (Step 13).

(19) In another configuration of the invention, the method sequence which is represented in FIG. 2 may be carried out in a similar way to the first embodiment explained above, in which case a further step of recompaction by hot isostatic pressing (Step 14) may additionally be carried out in the second embodiment. In the case of a molybdenum alloy with incorporated silicides, this may for example be carried out at a temperature of 1500 C. for four hours.

(20) In the third embodiment, the flowchart of which is shown in FIG. 3, the hot pressing of the powder in an evacuated and optionally precontoured capsule is replaced with hot isostatic pressing (Step 14), in which case thermoplastic shaping by isothermal die forging or hot die forging may additionally be carried out (Step 15). It is also conceivable, in the case of the method according to the flowchart in FIG. 3, to omit this hot isostatic pressing (Step 14) and instead carry out thermoplastic shaping exclusively by isothermal die forging or hot die forging.

(21) In a fourth embodiment (FIG. 4), which substantially corresponds to the first embodiment, in addition to the hot pressing (Step 12), subsequent thermoplastic shaping by die forging, isothermal die forging, extrusion, hammering, freeform forging or rolling may be carried out (Step 15).

(22) In the fifth embodiment (FIG. 5), which does not differ from the previous embodiments in terms of the provision of the powders (Step 10) and the mixing of the powders (Step 11), the steps of compaction and bonding of the powder particles are carried out separately, specifically on the one hand by cold isostatic pressing (Step 16) and on the other hand by sintering (Step 17). A unit produced in this way from the powder particles is then subjected to thermoplastic shaping (Step 15) in the form of die forging (isothermal die forging or hot die forging). As an alternative or in addition, the thermoplastic shaping may also be carried out by hot isostatic pressing by hammering, in particular swaging, extrusion, freeform forging or rolling.

(23) In a sixth embodiment (FIG. 6), the steps of compaction and bonding of the powders may be combined in one step, in particular by pressure sintering (Step 18).

(24) In the seventh embodiment (FIG. 7), as in the first embodiment, the previously provided powders are again initially mixed (Step 11). After the mixing, the powders are cold-pressed (Step 16) and subsequently sintered at temperatures of between 1000 C. and 1800 C. in a hydrogen atmosphere (Step 17). Hot isostatic pressing (HIP) is then carried out at from 1200 C. to 1500 C. for from two to six hours at a pressure of from 100 to 200 MPa (Step 14). In addition or as an alternative, isothermal die forging or hot die forging, as well as other forms of thermoplastic deformation such as swaging, extrusion, freeform forging or rolling may be carried out. Subsequently, a heat treatment may be carried out at a temperature in the range from 100 C. to 200 C. below the recrystallization temperature for from five to thirty hours in an air atmosphere or in an inert atmosphere, and cooling may be carried out in the furnace, so that internal stresses may be relaxed and/or corresponding structural adjustments may be carried out (Step 13). Depending on the material, the temperature during the heat treatment may, for example, lie between 1000 C. and 1500 C.

(25) In another embodiment (FIG. 8), the previously provided powders are again initially mixed, subsequently cold-pressed (Step 16) and again sintered at temperatures of between 1000 C. and 1800 C. in a hydrogen atmosphere (Step 17). A material unit obtained in this way is combined with other units, which have a different chemical composition, in such a way that, by layerwise melting in an electron beam furnace with subsequent solidification, a semifinished product is obtained which has different properties because of the differing chemical composition over the component (Step 19). It is thus possible to produce a semifinished product which has better ductility in one region than in another region, while conversely the creep resistance is lower in the ductile region than in the non-ductile region. Correspondingly, a turbine blade in which the ductile region forms the blade root and the creep-resistant region forms the blade surface could be produced from the semifinished product. The corresponding semifinished product is subsequently shaped by thermoplastic deformation to form the desired component (Step 15). Again, die forging, hammering, extrusion, freeform forging or rolling may be used as methods. A subsequent heat treatment (Step 13) may be carried out by means of an induction coil in an air atmosphere or in an inert atmosphere, specifically at temperatures in the range of from 100 C. to 200 C. below the recrystallization temperature for from five to thirty hours. The heat treatment with the induction coil may be carried out homogeneously over the entire component or partially, or with a temperature gradient. A partial heat treatment may be adapted to the different chemical compositions of the component.

(26) In another embodiment (FIG. 9), a unit is again formed from elemental powders by cold pressing and sintering in a hydrogen atmosphere at temperatures of between 1000 C. and 1800 C. The one or more corresponding units are then melted in an electron beam furnace and, during the solidification in the furnace, suitable temperature gradients are set up so that a directionally solidified semifinished product with anisotropic properties is formed (Step 20). For example, the creep resistance can be formed particularly well by the anisotropy set up in a privileged direction, so that this component direction is aligned in the future component, for example a turbine blade, according to the load direction in relation to the creep loading.

(27) The component produced thereby is in turn subjected to a thermoplastic shaping and a subsequent heat treatment, as they have been described in the two preceding embodiments.

(28) In another embodiment, a unit is again produced from elemental powders by cold pressing and sintering at temperatures of between 1000 C. and 1800 C. in a hydrogen atmosphere. In this embodiment as well, the units produced in this way are melted in an electron beam furnace and subsequently subjected to a thermoplastic method as well as a heat treatment, such as were described in the previous exemplary embodiments. The solidification, however, is carried out not as directional solidification as in the previous exemplary embodiment but as homogeneous solidification.

(29) By the described methods and embodiments, a process for producing components from metal-intermetallic composites (MIC), and in particular molybdenum alloy with incorporated intermetallic silicide compounds, is provided, which has a lower susceptibility to impurities and in particular to gas inclusions because of the method steps carried out, which improves the deformability of the material. The avoidance of impurities, for example inclusions, furthermore increases the reliability and lifetime of the component. This is also achieved by reducing the porosity by the thermoplastic shaping process, in which case the tensile strength may also be increased by the thermoplastic shaping. Overall, for the production of corresponding materials, fewer process steps are required, which are less elaborate, so that in particular an advantageous production method is obtained.

(30) While the present invention has been described with reference to exemplary embodiments, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.